Retractive pilot for circle cutters



April 25, 1950 J. F. D OOLEY RETRACTIVE PILOT FOR CIRCLE CUT'I'ERS Filed Oct. 4, 1946 V INVENTOR.

Patented Apr. 1950 f amm 2,505,23ii Luth a e ease QQTTERS- --D? l llhcel iv 11 Application qetober l, 19%,; Se ial No. 701,361

1 3 Claims.

"'Thepresent invention'ha's relationto improve 'mentspin means for producing circular-cuts of various sizes in sheets of metal or other matelTools-of the type referredto-are conventionally made with a central pilot which is insertable ina'h'ole in'thematerial tobe cut for thepurpose of guiding the cutter during the'cutting opera tion. "Frequently solid-discs are to--be produced and suchdisos could not be made with the pilot type of-cutt'er which requires the-presence of the projected element which will recede whenthe cutter is movdagainst the material to be out, but will functionas a .guidepin in connection with material'havi'ng'a" central perforation of a size to-receivesuch pins Another object is to providea cutter mecha nism of simple and sturdy-construction. Still another.object is to provide acutter mechanism which" may be held firmly in position on the material during the cutting"operationfwithout marringor otherwise 'injuringlthe surface thereof,

Another' object "is to provide a .cutte1"- mechanisin which{isquickly' and convenientlyfadju'st ableto perform great varieties, of circular cutting ioperations." I f I f .With these. and other objec s n;view,ltheiin' vent'ion resides inthe' combinations set forth in the following detailed description, and reference is invited to the accompanying drawings, of which:

Fig. 1 is a side elevational view, partly in section of a device embodying the invention;

Figs. 2 and 3 are, respectively, top and bottom views of the device;

Fig.4 is a right end view of a portion of the device of Fig. 1 with other parts of the device omitted or broken away;

Fig. 5 is a right end view of the tool holder of the device; and

Figs. 6, 7, and 8 illustrate a combination tool for use on the device and particularly adapted to cut rings and washers.

As illustrated in the drawings, the invention comprises a cylindrical bodyportion I which is axially perforated to provide a larger bottom recess I and a smaller recess I sunk into the top thereof. Aflplung-errl is' fitted m1 slide within-the recess I g ne 'thi'splunger is at the'bottomthere-f of counterbored to receive aresilient pad or plug yieldingly l projected, and a bolt 5; the head "of hich is seated in the upper bodyrecess l limits outward'f 'movementofthe 'plunger.

"The body'is shown made in the-sides thereof withjdiametrically opposed"recesses -I', I, in:

which the prongs" for legs of a *bifuifcated tool hoiderflfare seatedto "slide.- Tliei*head of this tool'holde'r" is semi=circular in shape and itf'is made with parallel slots or recesses 6 6 'of a'size to receive a cutting tool Ai The holder ism'ovable radially to adjust thefdevicato 'the diameter of thecut or cutstobe madei; 'Iti's important to note that thes'efslots areradia'lly spaced apart, and this'is done'in' orderthat the tool'may be moved from slot to slot to cuticircles of different diameters without disturbing the setting of the" tool "holder" in the g'roov'es'ofthe body portion or;

ir="preer1-ed,fa sepa a t l a Placed in" each fs'lotf The tool and tool holderfare clamped in'adjustedposition by means of screwss, 9.

ln o'peration, the deviceisset in the spindle of a'drill pre'ss ormilling machine and moved until the padf3 icont'acts" the 'niaterialjto be Jcut;

When thereupoiii the spindle is rotated and the deviceidepre's'sed;against the tension'of the spring 4;"fuintil the cutter reaches and sinks into the maj-g te'ri'alJ-it 'is' fdundthatthe pad will maintain the device firmly in position. A ball or roller'thrust bearingIWis set"i'ntoxthebody I to eliminate frictionb'etwee'n the spring and the body.

E'Attimesit maybe found'fdeisrable to make a *ce'nt'e'r"puncfimark in the material in order more conveniently to provide for correct positioning of the device. When such is provided, it is possible to mount a center guide pin I I within the plunger and to place a light spring I2 behind this guide, as indicated in Fig. 1. A shallow roove H is sunk into the side of this guide pin for engagement by a screw I3 to limit downward movement thereof. In cases where this guide pin is not to be used, it is merely required to push it inward, beyond the surface of the pad 3, and to advance the screw I3 until it clamps the pin firmly in this retracted position or, if preferred the guide pin may be detached.

For use in cutting circular rings and wedges, the cutter combination of Figs. 6 to 8 is found more convenient. This combination cutter consists of a'post I5, which is perforated near the bottom thereof to receive a rod I6, and the latter is lengthwise adjustable within the post. The

lower end of the post is shown slotted up from the bottom thereof to the said perforations and a bolt I1 is seated in this slotted portion to clamp the rod H5 in adjusted position.

A pair of cutter holders 18 are mounted on the rod in the manner best indicated in Fi 8. It is noticed that these holders are perforated to receive the rod in the same manner that the post [5 is perforated, and that they are similarly slotted to receive clamping bolts l9. In the lower end of each cutter holder is cut a slot at right angles to the slot at the upper end thereof of a size to receive a cutting tool 20, and a bolt 2i serves to clamp each cutting tool rigidly .in position. In order to maintain the rod l6 rigidly in clamped position, it is well to serrate the surface thereof, substantially as indicated at It in the drawings or, if preferred, the rod may be made rectangular in .cross section.

As illustrated in Figs. 6 and '7, these tool holdersmaybe variously arranged on one side or on bothsides of the post as may be found most convenient for particular operations. This type of combination tool is particularly designed for cutting thin material such as paper, cardboard or plastic sheets.

'While I have herein described and shown a preferred form of the invention, I do not intend thereby to be limited to the exact proportions and arrangements of parts and features shown, but reserve the right to embody modifications within the scope of the claims hereto appended.

I claim:

1. In a circle cutting tool, a tubular cylindrical body terminating in a shank at the top thereof and having a cylindrical recess axially sunk in the top and bottom surfaces thereof, the body having diametrically opposite parallel grooves in the side thereof for supporting therein a tool holder, a plunger fitted to slide within said bottom recess and terminating at the bottom in an enlarged head, said plunger having a threaded recess at the top thereof and a cylindrical recess at its bottom, a bolt seated in the threads of said plunger recess, said bolt having a head riding in the top recess of the body, a spring on the plunger between the body and the plunger head urging downward movement of the plunger, an. anti-friction thrust bearing between the end of the body and the spring, and a guide pin axially slidable in the bottom recess of the plunger. 7

2. In a circle cutting tool, a tubular cylindrical body terminating in a shank at the top thereof andhaving' a cylindrical recess axially sunk in the top and bottom surfaces thereof, the body having diametrically opposite parallel grooves in the side thereof for supporting therein a tool holder, a plunger fitted to slide within said bottom recess and terminating at the bottom in an enlarged head, said plunger having a threaded recess at the top thereof and a cylindrical recess 1 at its bottom, a bolt seated in the threads of said plunger recess, said bolt having a head riding in the top recess of the body, a spring on the plunger between the body and the plunger head urging downward movement of the plunger, an anti-friction thrust bearing between the end of the body and the spring, a guide pin seated for axial movement within the plunger, a spring urging said pin downward, and means limitin sliding movement of the pin.

3. In a circle cutting tool, a tubular cylindrical body terminating in a shank at the top thereof and having a cylindrical recess axially sunk in the top and bottom surfaces thereof, the body having diametrically opposite parallel grooves in the side thereof for supporting therein a tool.

holder, a plunger fitted to slide Within said bottom recess and terminating at the bottom in an enlarged annular head, a resilient pad seated in and downwardly projecting from the head, said plunger having a threaded recess at the top thereof and a cylindrical recess at its bottom, a bolt seated in the threads of said plunger recess, said bolt having a head riding in the top recess of the body, a spring on the plunger between the body and the plunger head urging downward movement of the plunger, an antifriction thrust bearing between the end of the body and the spring, a guide pin seated for axial movement within the plunger, a spring urging said pin downward, and means limiting sliding movement of theapin, said means being operable to lock the pin in retracted position within the plunger.

JOHN F. DOOLEY.

REFERENCES CITED The following references are of record in the file of this patent? UNITED STATES PATENTS Smith Aug. 27, 

